MORPHOLOGICAL AND GROWTH-CHARACTERISTICS OF LOW-WATER AND HIGH-WATER USE KENTUCKY BLUEGRASS CULTIVARS

As the competition for water increases, there is a need to conserve li mited water resources applied to irrigated turfgrass sites. Consistent with this effort is the identification of water conserving Kentucky b luegrass (Pea pratensis L.) because low consumptive water use may be i mportant in reducing irrigation requirements by enhancing drought resi stance. Low evapotranspiration (ET) rates under nonlimiting soil moist ure conditions have been associated with turfgrass morphology and grow th characteristics that increase canopy resistance to ET and reduce le af area components. Much of this previous research emphasized warm-sea son turfgrass. A greenhouse study was conducted to determine the relat ionship between morphological and growth characteristics in 61 Kentuck y bluegrass (KEG) cultivars and comparative water use, By means of clu ster analysis, the 61 KEG cultivars were categorized as either low-or high-water use cultivars based on ET rates evaluated in the growth cha mber across three evaporative demand environments (1.263, 1.664, and 2 .261 kPa VPD). Morphological and growth characteristics were assessed from unmowed, spaced plants and mowed turfgrass grown in fritted clay tilled lysimeters. Based on single plant morphology, low-water use cul tivars had 13% more horizontal leaf orientation, 6% narrower leaf text ure, 13% more lateral shoots per plant, 12% slower vertical leaf exten sion rate, 2% more leaves per shoot, and 7% shorter leaf blades and sh eaths than the high-water use cultivars. Based on turfgrass morphology from mowed lysimeters, the low-water use cultivars had 17% more horiz ontal leaf orientation, 10% narrower leaf texture, 15% more shoots, 4% slower vertical leaf extension rate, and 4% shorter leaf sheaths than the high-water use group. Canopy resistance to ET was not measured in this study; however, leaf angle (assumed component of canopy resistan ce) was the only plant characteristics evaluated under mon ed conditio ns whose correlation with turfgrass ET exceeded 0.50 in absolute value . Differences observed among water use groups based on single plant-an d turfgrass-morphology was not always consistent with the high canopy resistance to ET/low leaf area hypothesis. However, characteristics we re identified which may be useful in selecting for KBG with a low-wate r use pattern.